First principles study of effect of surface structure on chemical activity of Pt electrocatalysts in fuel cells

To facilitate commercialization of fuel cell systems as alternative energy device, the enhancement of Pt electrocatalysts activity is one of the most challenging issues. The first step to the solution is elucidating relationship between surface structure and chemical reactivity as electrocatalysis occurs on its surface. However, in spite of concerted experimental and theoretical research over the last decades, the detailed mechanism is still in debate. This thesis explores a structural sensitivity of the chemical reactivity in the Pt-based alloy electrocatalysts by combining ab-initio density functional theory (DFT) with relevant thermodynamic and kinetic approach. We developed a rigorous statistical mechanical formalism, which can parameterize the energetics obtained by first principles calculations as a function of surface topologies. This methodology enables kinetic Monte Carlo simulations to provide thermally equilibrated structures as a function of partial pressures of adsorbates and alloy compositions. With our consistent methods, we characterize surface structures on the atomic scale, and quantify chemical reactivity of various Pt-alloy model systems. Our methodology reproduced accurate and consistent results of available experimental measurements. We find that our methodology is considerably useful for studying the structural effect on the heterogeneous catalysis. Through the thesis, we understood better how surface structures evolve according to environmental conditions and hence, the structure-activity relationship, which is useful for design of electrocatalysts.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Han, Byungchan

Advisor dc:contributor.advisor

• Gerbrand Ceder.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/44313

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44313